1. Field of the Invention
The present invention relates to a polycarbonate-polyorganosiloxane copolymer and a resin composition comprising said copolymer. More particularly, the present invention relates to a novel polycarbonate-polyorganosiloxane copolymer having excellent flame resistance, impact resistance, transparency and mold releasing property and a resin composition comprising said copolymer and an inorganic filler, a pigment or other resins and having an excellent flow property, sliding property, solvent resistance or the like.
2. Description of Related Art
As copolymerized polycarbonates containing halogen and having flame resistance, various copolymers have heretofore been proposed. Examples of such copolymer are: a copolymer of tetrabromobisphenol A (TBA) and bisphenol A (BPA) (Japanese Patent Publications 1971-40715 and 1972-24660), a copolymer of tetrabromobisphenolsulfone (TBS) and BPA (Japanese Patent Application Laid Open No. 1976-123294), a copolymer of a statistical mixture of halogenated bisphenol and BPA (Japanese Patent Application Laid Open No. 1976-136796), a blend of a copolymer of thiodiphenol (TDP) and BPA and a copolymer of tetrabromobisphenol A (TBA) and BPA (Japanese Patent Application Laid Open Nos. 1977-140597 and 1979-50065) and a copolymer of tetrabromothiodiphenol (TBTDP) and BPA (Japanese Patent Application Laid Open No. 1981-99226).
These copolymers are obtained by copolymerization of halogenated bisphenols in which benzene rings of bisphenols are substituted with halogen to contain necessary amount of halogen for providing flame resistance.
However, these copolymers have a drawback that these halogenated bisphenols have to be used in relatively large amounts and, accordingly, mechanical strength (particularly, impact strength) of the polycarbonates has to be sacrificed.
As another kind of polycarbonate containing halogen, a polycarbonate prepared by using a halogenated phenol as the terminator of chain end was also disclosed (Japanese Patent Publication 1971-40715). However, simultaneous exhibition of both of the flame resistance and the mechanical strength could not be realized in this case either.
As a method of improving the drawback described above, methods of copolymerizing BPA and a halogenated bisphenol A by using a polyhalogenophenol as the chain terminator are known (for example, Japanese Patent Application Laid Open Nos. 1989-79227, 1989-79228 and 1991-200833). Even though the flame resistance and the mechanical strength can be provided simultaneously by this method, the present inventors made Further study and succeeded in achieving still better flame resistance and impact resistance.
The present inventors discovered that a polycarbonate-polyorganosiloxane copolymer comprising a specific polycarbonate derived from a bisphenol and a halogenated bisphenol and a specific polyorgnosiloxane polymer and a resin composition comprising said copolymer and an inorganic filler, a pigment or other resins have the properties superior to the heretofore known materials described above. The present invention was completed on the basis of the discovery.